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| Titel |
Near surface shear wave velocity in Bucharest, Romania |
| VerfasserIn |
M. Steht, B. Jaskolla, J. R. R. Ritter |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 6 ; Nr. 8, no. 6 (2008-12-01), S.1299-1307 |
| Datensatznummer |
250005901
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| Publikation (Nr.) |
 copernicus.org/nhess-8-1299-2008.pdf |
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| Zusammenfassung |
| Bucharest, the capital of Romania with nearly
2 1/2 million inhabitants, is
endangered by the strong earthquakes in the Vrancea seismic zone. To obtain
information on the near surface shear-wave velocity Vs structure and to
improve the available microzonations we conducted seismic refraction
measurements in two parks of the city. There the shallow Vs structure is
determined along five profiles, and the compressional-wave velocity (Vp)
structure is obtained along one profile. Although the amount of data
collected is limited, they offer a reasonable idea about the seismic
velocity distribution in these two locations. This knowledge is useful for a
city like Bucharest where seismic velocity information so far is sparse and
poorly documented. Using sledge-hammer blows on a steel plate and a
24-channel recording unit, we observe clear shear-wave arrivals in a very
noisy environment up to a distance of 300 m from the source. The Vp model
along profile 1 can be correlated with the known near surface sedimentary
layers. Vp increases from 320 m/s near the surface to 1280 m/s above 55–65 m
depth. The Vs models along all five profiles are characterized by low Vs
(<350 m/s) in the upper 60 m depth and a maximum Vs of about 1000 m/s below this
depth. In the upper 30 m the average Vs30 varies from 210 m/s to 290 m/s.
The Vp-Vs relations lead to a high Poisson's ratio of 0.45–0.49 in the upper
~60 m depth, which is an indication for water-saturated clayey
sediments. Such ground conditions may severely influence the ground motion
during strong Vrancea earthquakes. |
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